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Date: Wed, 10 Jul 2013 14:18:28 -0700
From: Tom Herbert <therbert@...gle.com>
To: John Fastabend <john.fastabend@...il.com>
Cc: Stephen Hemminger <stephen@...workplumber.org>,
ben@...adent.org.uk,
"Brandeburg, Jesse" <jesse.brandeburg@...el.com>,
Linux Netdev List <netdev@...r.kernel.org>,
Jeff Kirsher <jeffrey.t.kirsher@...el.com>
Subject: Re: [RFC PATCH] net: add a rate_limit attribute to netdev_queue and a rtnetlink
John, thanks for posting this.
Should we have separate guaranteed and maximum rate? Will this be
usable in the case that more than one queue shares a rate? Do you
think other parameters, like priority weights should be done the same
way?
Tom
On Wed, Jul 10, 2013 at 7:04 AM, John Fastabend
<john.fastabend@...il.com> wrote:
> Add a rate_limit attribute to netdev_queue and a corresponding
> ndo ops to pass the parameter to the driver. Also provide an
> rtnetlink attribute to dump and set arbitrary queue attributes
> the first of which is the rate_limit.
>
> Netlink attribute layout shown here,
>
> /* Queue Attributes management
> * Nested layout of queue attributes is:
> * [IFLA_QUEUE_ATTRIBS]
> * [IFLA_QUEUE_ATTRIB]
> * [IFLA_QUEUE_INDEX] <required>
> * [IFLA_QUEUE_RATE] <optional>
> * [IFLA_QUEUE_ATTRIB]
> * [...]
> */
>
> Adding this as a queue attribute and _not_ a qdisc option allows
> using rate limits with qdisc schemes that may not align with tx rings
> and also allows using QOS schemes along with rate limits.
>
> A sample implementation is provided for ixgbe. Any improvements or
> suggestions welcome I would also be interested to know if this works
> with other hardware and if Mbps is a good default unit.
>
> The ndo op is only called when the netlink API is invoked, so drivers
> may need to adjust internal registers on link events (speed changes)
> as needed. More attributes can be added as needed.
>
> A test patch for iproute2 will be provided.
>
> Signed-off-by: John Fastabend <john.r.fastabend@...el.com>
> ---
> drivers/net/ethernet/intel/ixgbe/ixgbe_main.c | 16 ++++
> drivers/net/ethernet/intel/ixgbe/ixgbe_sriov.c | 47 +++++++++++--
> drivers/net/ethernet/intel/ixgbe/ixgbe_sriov.h | 2 +
> include/linux/netdevice.h | 14 ++++
> include/uapi/linux/if_link.h | 24 ++++++
> net/core/rtnetlink.c | 90 ++++++++++++++++++++++++
> 6 files changed, 187 insertions(+), 6 deletions(-)
>
> diff --git a/drivers/net/ethernet/intel/ixgbe/ixgbe_main.c b/drivers/net/ethernet/intel/ixgbe/ixgbe_main.c
> index 047ebaa..6a9b99c 100644
> --- a/drivers/net/ethernet/intel/ixgbe/ixgbe_main.c
> +++ b/drivers/net/ethernet/intel/ixgbe/ixgbe_main.c
> @@ -5579,6 +5579,19 @@ static void ixgbe_check_hang_subtask(struct ixgbe_adapter *adapter)
>
> }
>
> +static void ixgbe_reset_rate_limits(struct ixgbe_adapter *adapter)
> +{
> + struct net_device *dev = adapter->netdev;
> + int i;
> +
> + for (i = 0; i < dev->real_num_tx_queues; i++) {
> + struct netdev_queue *q = netdev_get_tx_queue(dev, i);
> + u32 rate = q->rate_limit;
> +
> + ixgbe_set_rate_limit(adapter->netdev, i, &rate);
> + }
> +}
> +
> /**
> * ixgbe_watchdog_update_link - update the link status
> * @adapter: pointer to the device adapter structure
> @@ -5620,6 +5633,8 @@ static void ixgbe_watchdog_update_link(struct ixgbe_adapter *adapter)
>
> adapter->link_up = link_up;
> adapter->link_speed = link_speed;
> +
> + ixgbe_reset_rate_limits(adapter);
> }
>
> static void ixgbe_update_default_up(struct ixgbe_adapter *adapter)
> @@ -7244,6 +7259,7 @@ static const struct net_device_ops ixgbe_netdev_ops = {
> .ndo_fdb_add = ixgbe_ndo_fdb_add,
> .ndo_bridge_setlink = ixgbe_ndo_bridge_setlink,
> .ndo_bridge_getlink = ixgbe_ndo_bridge_getlink,
> + .ndo_set_ratelimit = ixgbe_set_rate_limit,
> };
>
> /**
> diff --git a/drivers/net/ethernet/intel/ixgbe/ixgbe_sriov.c b/drivers/net/ethernet/intel/ixgbe/ixgbe_sriov.c
> index 1e7d587..1ea78f1 100644
> --- a/drivers/net/ethernet/intel/ixgbe/ixgbe_sriov.c
> +++ b/drivers/net/ethernet/intel/ixgbe/ixgbe_sriov.c
> @@ -1107,17 +1107,14 @@ static int ixgbe_link_mbps(struct ixgbe_adapter *adapter)
> }
> }
>
> -static void ixgbe_set_vf_rate_limit(struct ixgbe_adapter *adapter, int vf)
> +static u32 ixgbe_bcnrc_from_rate(struct ixgbe_adapter *adapter,
> + u16 tx_rate, int link_speed)
> {
> - struct ixgbe_ring_feature *vmdq = &adapter->ring_feature[RING_F_VMDQ];
> - struct ixgbe_hw *hw = &adapter->hw;
> u32 bcnrc_val = 0;
> - u16 queue, queues_per_pool;
> - u16 tx_rate = adapter->vfinfo[vf].tx_rate;
>
> if (tx_rate) {
> /* start with base link speed value */
> - bcnrc_val = adapter->vf_rate_link_speed;
> + bcnrc_val = link_speed;
>
> /* Calculate the rate factor values to set */
> bcnrc_val <<= IXGBE_RTTBCNRC_RF_INT_SHIFT;
> @@ -1131,6 +1128,11 @@ static void ixgbe_set_vf_rate_limit(struct ixgbe_adapter *adapter, int vf)
> bcnrc_val |= IXGBE_RTTBCNRC_RS_ENA;
> }
>
> + return bcnrc_val;
> +}
> +
> +static void ixgbe_set_xmit_compensation(struct ixgbe_hw *hw)
> +{
> /*
> * Set global transmit compensation time to the MMW_SIZE in RTTBCNRM
> * register. Typically MMW_SIZE=0x014 if 9728-byte jumbo is supported
> @@ -1146,6 +1148,39 @@ static void ixgbe_set_vf_rate_limit(struct ixgbe_adapter *adapter, int vf)
> default:
> break;
> }
> +}
> +
> +int ixgbe_set_rate_limit(struct net_device *dev, int index, u32 *tx_rate)
> +{
> + struct ixgbe_adapter *a = netdev_priv(dev);
> + struct ixgbe_hw *hw = &a->hw;
> + int linkspeed = ixgbe_link_mbps(a);
> + u8 reg_idx = a->tx_ring[index]->reg_idx;
> + u32 bcnrc = ixgbe_bcnrc_from_rate(a, *tx_rate, linkspeed);
> +
> + /* rate limit cannot be less than 10Mbs */
> + if (*tx_rate && (*tx_rate <= 10))
> + return -EINVAL;
> +
> + ixgbe_set_xmit_compensation(hw);
> +
> + IXGBE_WRITE_REG(hw, IXGBE_RTTDQSEL, reg_idx);
> + IXGBE_WRITE_REG(hw, IXGBE_RTTBCNRC, bcnrc);
> +
> + return 0;
> +}
> +
> +static void ixgbe_set_vf_rate_limit(struct ixgbe_adapter *adapter, int vf)
> +{
> + struct ixgbe_ring_feature *vmdq = &adapter->ring_feature[RING_F_VMDQ];
> + struct ixgbe_hw *hw = &adapter->hw;
> + u32 bcnrc_val = 0;
> + u16 queue, queues_per_pool;
> + u16 tx_rate = adapter->vfinfo[vf].tx_rate;
> +
> + bcnrc_val = ixgbe_bcnrc_from_rate(adapter, tx_rate,
> + adapter->vf_rate_link_speed);
> + ixgbe_set_xmit_compensation(hw);
>
> /* determine how many queues per pool based on VMDq mask */
> queues_per_pool = __ALIGN_MASK(1, ~vmdq->mask);
> diff --git a/drivers/net/ethernet/intel/ixgbe/ixgbe_sriov.h b/drivers/net/ethernet/intel/ixgbe/ixgbe_sriov.h
> index 4713f9f..d8b4bbe 100644
> --- a/drivers/net/ethernet/intel/ixgbe/ixgbe_sriov.h
> +++ b/drivers/net/ethernet/intel/ixgbe/ixgbe_sriov.h
> @@ -56,5 +56,7 @@ static inline void ixgbe_set_vmvir(struct ixgbe_adapter *adapter,
> IXGBE_WRITE_REG(hw, IXGBE_VMVIR(vf), vmvir);
> }
>
> +int ixgbe_set_rate_limit(struct net_device *dev, int index, u32 *tx_rate);
> +
> #endif /* _IXGBE_SRIOV_H_ */
>
> diff --git a/include/linux/netdevice.h b/include/linux/netdevice.h
> index 09b4188..0e67b09 100644
> --- a/include/linux/netdevice.h
> +++ b/include/linux/netdevice.h
> @@ -574,6 +574,7 @@ struct netdev_queue {
> #ifdef CONFIG_BQL
> struct dql dql;
> #endif
> + u32 rate_limit;
> } ____cacheline_aligned_in_smp;
>
> static inline int netdev_queue_numa_node_read(const struct netdev_queue *q)
> @@ -932,6 +933,16 @@ struct netdev_fcoe_hbainfo {
> * that determine carrier state from physical hardware properties (eg
> * network cables) or protocol-dependent mechanisms (eg
> * USB_CDC_NOTIFY_NETWORK_CONNECTION) should NOT implement this function.
> + *
> + * int (*ndo_set_ratelimit)(struct net_device *dev,
> + * int queue_index, u32 *maxrate)
> + * Called to set the rate limit in Mpbs of the specified queue_index
> + * setting the limit to maxrate. It is expected that hardware may
> + * quantize the rate limits. In these cases the driver should guarantee the
> + * specified maxrate is not exceeded and return the set value in maxrate.
> + * Zero should be returned on success otherwise use appropriate error code.
> + * Drivers must handle any updates required with link speed changes within
> + * normal driver code paths.
> */
> struct net_device_ops {
> int (*ndo_init)(struct net_device *dev);
> @@ -1060,6 +1071,9 @@ struct net_device_ops {
> struct nlmsghdr *nlh);
> int (*ndo_change_carrier)(struct net_device *dev,
> bool new_carrier);
> + int (*ndo_set_ratelimit)(struct net_device *dev,
> + int queue_index,
> + u32 *max_rate);
> };
>
> /*
> diff --git a/include/uapi/linux/if_link.h b/include/uapi/linux/if_link.h
> index 03f6170..67a353c 100644
> --- a/include/uapi/linux/if_link.h
> +++ b/include/uapi/linux/if_link.h
> @@ -143,6 +143,7 @@ enum {
> IFLA_NUM_TX_QUEUES,
> IFLA_NUM_RX_QUEUES,
> IFLA_CARRIER,
> + IFLA_QUEUE_ATTRIBS,
> __IFLA_MAX
> };
>
> @@ -449,6 +450,29 @@ struct ifla_port_vsi {
> __u8 pad[3];
> };
>
> +/* Queue Attributes management
> + * Nested layout of queue attributes is:
> + * [IFLA_QUEUE_ATTRIBS]
> + * [IFLA_QUEUE_ATTRIB]
> + * [IFLA_QUEUE_INDEX] <required>
> + * [IFLA_QUEUE_RATE] <optional>
> + * [IFLA_QUEUE_ATTRIB]
> + * [...]
> + */
> +enum {
> + IFLA_QUEUE_ATTRIB_UNSPEC,
> + IFLA_QUEUE_ATTRIB, /* nest */
> + __IFLA_QUEUE_ATTRIB_MAX,
> +};
> +#define IFLA_QUEUE_ATTRIB_MAX (__IFLA_QUEUE_ATTRIB_MAX - 1)
> +
> +enum {
> + IFLA_QUEUE_UNSPEC,
> + IFLA_QUEUE_INDEX, /* __u32 */
> + IFLA_QUEUE_RATE, /* __u32 */
> + __IFLA_QUEUE_MAX,
> +};
> +#define IFLA_QUEUE_MAX (__IFLA_QUEUE_MAX - 1)
>
> /* IPoIB section */
>
> diff --git a/net/core/rtnetlink.c b/net/core/rtnetlink.c
> index 9007533..d7ff1c2 100644
> --- a/net/core/rtnetlink.c
> +++ b/net/core/rtnetlink.c
> @@ -846,6 +846,45 @@ static int rtnl_port_fill(struct sk_buff *skb, struct net_device *dev)
> return 0;
> }
>
> +static int rtnl_queue_fill(struct sk_buff *skb, struct net_device *dev)
> +{
> + int i;
> + struct nlattr *attribs, *attrib = NULL;
> +
> + attribs = nla_nest_start(skb, IFLA_QUEUE_ATTRIBS);
> + if (!attribs)
> + return -EMSGSIZE;
> +
> + for (i = 0; i < dev->real_num_tx_queues; i++) {
> + struct netdev_queue *q = netdev_get_tx_queue(dev, i);
> +
> + if (!q->rate_limit)
> + continue;
> +
> + attrib = nla_nest_start(skb, IFLA_QUEUE_ATTRIB);
> + if (!attrib) {
> + nla_nest_cancel(skb, attribs);
> + return -EMSGSIZE;
> + }
> +
> + if (nla_put_u32(skb, IFLA_QUEUE_INDEX, i) ||
> + nla_put_u32(skb, IFLA_QUEUE_RATE, q->rate_limit)) {
> + nla_nest_cancel(skb, attrib);
> + nla_nest_cancel(skb, attribs);
> + return -EMSGSIZE;
> + }
> +
> + nla_nest_end(skb, attrib);
> + }
> +
> + if (attrib)
> + nla_nest_end(skb, attribs);
> + else
> + nla_nest_cancel(skb, attribs);
> +
> + return 0;
> +}
> +
> static int rtnl_fill_ifinfo(struct sk_buff *skb, struct net_device *dev,
> int type, u32 pid, u32 seq, u32 change,
> unsigned int flags, u32 ext_filter_mask)
> @@ -997,6 +1036,9 @@ static int rtnl_fill_ifinfo(struct sk_buff *skb, struct net_device *dev,
> if (rtnl_port_fill(skb, dev))
> goto nla_put_failure;
>
> + if (rtnl_queue_fill(skb, dev))
> + goto nla_put_failure;
> +
> if (dev->rtnl_link_ops) {
> if (rtnl_link_fill(skb, dev) < 0)
> goto nla_put_failure;
> @@ -1150,6 +1192,11 @@ static const struct nla_policy ifla_port_policy[IFLA_PORT_MAX+1] = {
> [IFLA_PORT_RESPONSE] = { .type = NLA_U16, },
> };
>
> +static const struct nla_policy ifla_queue_policy[IFLA_QUEUE_MAX+1] = {
> + [IFLA_QUEUE_INDEX] = { .type = NLA_U32},
> + [IFLA_QUEUE_RATE] = { .type = NLA_U32},
> +};
> +
> struct net *rtnl_link_get_net(struct net *src_net, struct nlattr *tb[])
> {
> struct net *net;
> @@ -1503,6 +1550,49 @@ static int do_setlink(struct net_device *dev, struct ifinfomsg *ifm,
> goto errout;
> modified = 1;
> }
> + if (tb[IFLA_QUEUE_ATTRIBS]) {
> + struct nlattr *attr;
> + int rem;
> +
> + nla_for_each_nested(attr, tb[IFLA_QUEUE_ATTRIBS], rem) {
> + struct nlattr *queue[IFLA_QUEUE_MAX+1];
> + struct netdev_queue *q = NULL;
> + unsigned int qindex, qrate;
> +
> + if (nla_type(attr) != IFLA_QUEUE_ATTRIB)
> + continue;
> +
> + err = nla_parse_nested(queue, IFLA_QUEUE_MAX,
> + attr, ifla_queue_policy);
> + if (err < 0)
> + goto errout;
> +
> + err = -EINVAL;
> + if (queue[IFLA_QUEUE_INDEX]) {
> + qindex = nla_get_u32(queue[IFLA_QUEUE_INDEX]);
> + if (qindex >= dev->real_num_tx_queues)
> + goto errout;
> +
> + q = netdev_get_tx_queue(dev, qindex);
> + } else {
> + goto errout;
> + }
> +
> + err = -EOPNOTSUPP;
> + if (queue[IFLA_QUEUE_RATE]) {
> + if (!ops->ndo_set_ratelimit)
> + goto errout;
> +
> + qrate = nla_get_u32(queue[IFLA_QUEUE_RATE]);
> + err = ops->ndo_set_ratelimit(dev,
> + qindex, &qrate);
> + if (err < 0)
> + goto errout;
> + q->rate_limit = qrate;
> + modified = 1;
> + }
> + }
> + }
>
> if (tb[IFLA_AF_SPEC]) {
> struct nlattr *af;
>
--
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